1. Technical Field of the Invention
The present invention relates generally to a collision detecting apparatus which may be employed to detect an accidental vehicle collision for activating an automotive airbag safety unit. More particularly, the invention is directed to an improved structure of a collision detecting apparatus designed to provide for ease of assembly.
2. Background Art
Japanese Patent First Publication No. 3-274464 discloses a conventional collision detecting unit for automotive vehicles. This unit includes generally first and second assemblies. The first assembly includes a casing, a mass member, a main spring for urging the mass member in a given direction within the casing, and a stopper for restricting the movement of the mass member against the spring force of the main spring. The second assembly includes a movable contact, a casing having disposed therein a sub-spring to bias the movable contact onto the mass member of the first assembly to form a preselected contact gap to stationary contacts. Building the second assembly into the first assembly is accomplished by inserting a flange of the casing of the second assembly into an opening of the casing of the first assembly and thermally crimping a peripheral thin-walled edge of the opening.
However, since in such a structure of the collision detecting unit, the first and second assemblies must be combined after each having been assembled completely, assembling processes become complex, requiring more critical tolerances of the respective parts of the unit.